322 ROBERT T. HANCE 



to appear. However, this line is evidently pure for this char- 

 acter since exconjugants when separated produced offspring 

 which showed no variation in the percentage of vacuoles from 

 the number possessed before conjugation began as is indicated 

 by the following observations. Single conjugants of the vari- 

 ous combination of vacuole number were isolated and allowed 

 to separate and divide a number of times and then examined. 

 The results were not different from those obtained on unconju- 

 gated forms. To take two typical cases in which the conju- 

 gants were isolated, and allowed to separate and divide for a 

 week or more. 



Conjugant 2X3: per cent 



Two-vacuoled paramoecia 31 



Three-vacuoled paramoecia 69 



Conjugant 2X4: 



Two-vacuoled paramoecia 32 



Three-vacuoled paramoecia 69 



The number of two-vacuoled forms here is slightly higher than 

 the average due probably to the rapid division stimulated by 

 fresh hay infusion. 



In one instance the exconjugants were allowed to divide twice, 

 producing eight animals in all, and then each animal was iso- 

 lated in a separate watch crystal and allowed to multiply for 

 some time. This was done to determine whether any difference 

 in potentiality would crop out due to the redistribution of the 

 micronucleus. No change was observed. 



No effect can be ascribed to conjugation other than a tem- 

 porary increase in the percentage of two-vacuoled forms and 

 a corresponding decrease of the threes and fours. This may 

 indicate that conjugation speeds up the division rate somewhat 

 as it has been shown before that increased rate of di\'ision 

 results in individuals with fewer contractile vacuoles than is 

 the case when the division rate is slow. 



Chart 5 beginning with March 19 when conjugation began in 

 cultures 1, 3 and 5 shows a slight rise in the 'two' line (marked 

 1-3-5) and a fall in the 'three' line for the same cultures both, 

 however, returning to very nearly the same point on April 6 



